“The Last Supper”, fresco (453 × 975 cm) by Andrea del Castagno, about 1447, preserved on the west wall of the refectory of the monastery of Sant'Apollonia in Florence, now the museum of the Cenacle of Sant'Apollonia. Detail of Saint Thomas who appears depicted in an attitude of clear skepticism, with his head turned upwards and his hand on his chin to support him: this is, in fact, the apostle who in the Gospel affirms his need to see to believe.